Microporous crystalline material comprising a molecular sieve or zeolite having an 8-ring pore opening structure and methods of making and using same

ABSTRACT

There is disclosed a hydrothermally stable microporous crystalline material comprising a molecular sieve or zeolite having an 8-ring pore opening structure, such as SAPO-34 or aluminosilicate zeolite, able to retain a specific percentage of its surface area and micropore volume after treatment with heat and moisture, such as at least 80% of its surface area and micropore volume after exposure to temperatures of up to 900° C. in the presence of up to 10 volume percent water vapor for a time ranging from 1 to 16 hours. Methods of using the disclosed crystalline material, such as in the SCR of NO x  in exhaust gas are also disclosed, as are methods of making such materials.

This application claims the benefit of domestic priority to U.S.Provisional Patent Application No. 60/907,206, filed Mar. 26, 2007,which is herein incorporated by reference in its entirety.

The present disclosure is related to hydrothermally stable microporouscrystalline materials comprising a molecular sieve or zeolite having an8-ring pore opening structure, such as SAPO-34 or aluminosilicatezeolite, that is able to retain a specific percentage of its surfacearea and micropore volume after treatment with heat and moisture. Thepresent disclosure is also related to a method of making and methods ofusing the disclosed crystalline materials, such as in reducingcontaminants in exhaust gases. Such methods include the selectivecatalytic reduction (“SCR”) of exhaust gases contaminated with nitrogenoxides (“NO_(x)”).

Microporous crystalline materials and their uses as catalysts andmolecular sieve adsorbents are known in the art. Microporous crystallinematerials include crystalline aluminosilicate zeolites, metalorganosilicates, and aluminophosphates, among others. One catalytic useof the materials is in the SCR of NO_(x) with ammonia in the presence ofoxygen and in the conversion process of different feed stocks, such asan oxygenate to olefin reaction system.

Medium to large pore zeolites containing metals, such as ZSM-5 and Beta,are also known in the art for SCR of NO_(x) using reductants, such asammonia.

A class of silicon-substituted aluminophosphates, which are bothcrystalline and microporous and exhibit properties characteristic ofboth aluminosilicate zeolites and aluminophosphates, are known in theart and disclosed in U.S. Pat. No. 4,440,871. Silicoaluminophosphates(SAPOs) are synthetic materials having a three-dimensional microporousaluminophosphate crystalline framework with silicon incorporatedtherein. The framework structure consists of PO₂ ⁺, AlO₂ ⁻, and SiO₂tetrahedral units. The empirical chemical composition on an anhydrousbasis is:mR:(Si_(x)Al_(y)P_(z))O₂wherein, R represents at least one organic templating agent present inthe intracrystalline pore system; m represents the moles of R presentper mole of (Si_(x)Al_(y)P_(z))O₂ and has a value from zero to 0.3; andx, y, and z represent the mole fractions of silicon, aluminum, andphosphorous, respectively, present as tetrahedral oxides.

U.S. Pat. No. 4,961,917 discloses a method for the reduction of NO_(x)with ammonia using a certain class of zeolite catalysts that aresulfur-tolerant, especially when the zeolites are promoted with apromoter such as iron or copper. The zeolites disclosed therein havepore diameters of at least 7 Angstroms and are selected from the groupsincluding USY, Beta, and ZSM-20. The catalysts employed therein maintaingood catalytic properties under high temperature conditions of use, fromabout 250-600° C.

U.S. Pat. No. 5,451,387 discloses a method for improving the reductionactivity of the zeolite catalyst at temperatures below 400° C., withoutadversely affecting the reduction capacity above 400° C., by introducingiron into an intermediate pore size zeolite, which are identified asZSM-5 type zeolites. U.S. Pat. No. 6,914,026 discloses an iron-promotedaluminosilicate zeolite with improved hydrothermal stability and goodcatalytic activity under high temperatures, e.g., 400° C. and above, inthe presence of sulfur compounds. U.S. Pat. Nos. 6,689,709 and 7,118,722disclose stabilized iron and/or copper promoted zeolite catalysts forNO_(x) reduction, wherein the zeolites include USY, Beta, and/or ZSM-20,and have pore diameters of at least 7 Angstroms. U.S. Pat. No. 6,890,501discloses Beta-zeolites loaded with iron for the SCR of NO_(x) and N₂Owith ammonia, wherein the zeolite was prepared by ion-exchange orimpregnation.

U.S. Pat. No. 5,516,497 discloses a metal-promoted zeolite catalyst anda method for the catalytic reduction of NO_(x) with ammonia using thecatalysts in stages. The first catalyst is promoted with not more thanabout 1% by weight of iron and/or copper promoter, and the secondcatalyst is promoted with more than about 1% by weight of iron and/orcopper promoter. The selectivity of the catalyst, favoring eitherreduction of NO_(x) or ammonia, can be tailored by controlling thecontent of the promoting metal. By utilizing suitable zeolite materials,high temperature gaseous streams, up to about 600° C., may be treatedwithout seriously affecting the life or efficiency of the catalyst.

SUMMARY

Generally, the present disclosure provides a hydrothermally stablemicroporous crystalline material comprising a silicoaluminophosphate(SAPO) molecular sieve or aluminosilicate zeolite having an 8-ring poreopening structure, such as microporous crystalline compositionscomprising SAPO-34, SAPO-18, and high-silica chabazite. The crystallinematerial according to one embodiment of the present disclosure is ableto retain at least 80% of its surface area and micropore volume afterexposure to temperatures of up to 900° C. in the presence of up to 10vol. % water vapor for a time ranging from 1 to 16 hours.

In one embodiment, the microporous crystalline material comprisesSAPO-34, having an initial surface area of at least 650 m²/g, whereinthe surface area, after being treated at 700-900° C. and 10 vol. % watervapor for a time ranging from 1 to 16 hours, is at least 90% of theinitial surface area.

In another aspect of the invention, a microporous crystalline materialis chosen from SAPO molecular sieves and aluminosilicate zeolites havingan 8-ring pore opening structure defined by the Structure Commission ofthe International Zeolite Association chosen from: AEI, AFT, AFX, CHA,DDR, ERI, ITE, ITW, KFI, LEV, LTA, PAU, RHO, and UFI, wherein thematerial retains at least 80% of its surface area and micropore volumeafter exposure to temperatures of up to 900° C. in the presence of up to10 vol. % water vapor for a time ranging from 1 to 16 hours.

In another aspect of the present disclosure, the microporous crystallinematerials are cation exchanged, for example exchanged with iron orcopper. In one embodiment, the material, such as SAPO-34 and high-silicachabazite, is cation exchanged with iron, wherein the iron oxidecomprises at least 0.20 weight percent of the total weight of thematerial. In another embodiment, the material, such as SAPO-34 andhigh-silica chabazite, is cation exchanged with copper, wherein copperoxide comprises at least 1.0 weight percent of the total weight of thematerial.

Other aspects of the present disclosure include methods of SCR of NO_(x)in exhaust gas. One such method comprises contacting, in the presence ofammonia or urea, exhaust gas with a hydrothermally stable microporouscrystalline material comprising a molecular sieve or zeolite having an8-ring pore opening structure, including SAPO-34, SAPO-18, andhigh-silica chabazite, wherein the crystalline material retains at least80% of its surface area and micropore volume after exposure totemperatures of up to 900° C. in the presence of up to 10 vol. % watervapor for a time ranging from 1 to 16 hours.

Another aspect of the disclosed method comprises contacting, in thepresence of ammonia or urea, exhaust gas with a microporous crystallinematerial chosen from molecular sieves and zeolites having an 8-ring poreopening structure defined by the Structure Commission of theInternational Zeolite Association chosen from: AEI, AFT, AFX, CHA, DDR,ERI, ITE, ITW, KFI, LEV, LTA, PAU, RHO, and UFI, wherein the materialretains at least 80% of its surface area and micropore volume afterexposure to temperatures of up to 900° C. in the presence of up to 10vol. % water vapor for a time ranging from 1 to 16 hours.

Another aspect of the disclosed method comprises contacting, in thepresence of ammonia or urea, exhaust gas with a hydrothermally stablemicroporous material comprising a molecular sieve or zeolite having an8-ring pore opening structure, wherein the microporous materialcomprises iron and/or copper and retains at least 80% of its surfacearea and micropore volume after exposure to temperatures of up to 900°C. in the presence of up to 10 vol. % water vapor for up to 1 hour.

There is also disclosed a method for making a microporous crystallinematerial comprising a molecular sieve or zeolite having an 8-ring poreopening structure, the method comprising mixing sources of alumina,silica, and optionally phosphate in case of SAPOs, with a TEAOH solutionor an organic structural directing agent (SDA) and water to form a gel,heating the gel in an autoclave at a temperature ranging from 150 to180° C. for a time ranging from 12-60 hours to form a product, coolingand optionally washing the product in water, calcining the product toform a molecular sieve or zeolite having an 8-ring pore openingstructure, wherein the crystalline material retains at least 80% of itssurface area and micropore volume after exposure to temperatures of upto 900° C. in the presence of up to 10 vol. % water vapor for a timeranging from 1 to 16 hours.

Aside from the subject matter discussed above, the present disclosureincludes a number of other exemplary features such as those explainedhereinafter. It is to be understood that both the foregoing descriptionand the following description are exemplary only.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying figures are incorporated in, and constitute a part ofthis specification.

FIG. 1 is a SEM of the SAPO-34 material described in Example 1, beforeaging or cation-exchange.

FIG. 2 is a SEM of the SAPO-34 material described in Example 2, beforeaging or cation-exchange.

FIG. 3 is a XRD of the SAPO-34 material described in Example 1, beforeaging or cation-exchange.

FIG. 4 is a XRD of the SAPO-34 material described in Example 2, beforeaging or cation-exchange.

FIG. 5 is a XRD of the Cu-exchanged SAPO-34 material described inExample 1 after hydrothermal aging at 800° C.

FIG. 6 is a XRD of the Cu-exchanged SAPO-34 material described inExample 2 after hydrothermal aging at 800° C.

FIG. 7 is a SEM of the SAPO-34 material described in Comparative Example2, before aging or cation-exchange.

DEFINITIONS

“Hydrothermally stable” means having the ability to retain a certainpercentage of initial surface area and/or microporous volume afterexposure to elevated temperature and/or humidity conditions (compared toroom temperature) for a certain period of time. For example, in oneembodiment, it is intended to mean retaining at least 80%, such as atleast 85%, at least 90%, or even at least 95%, of its surface area andmicropore volume after exposure to conditions simulating those presentin an automobile exhaust, such as temperatures ranging up to 900° C. inthe presence of up to 10 volume percent (vol %) water vapor for timesranging from up to 1 hour, or even up to 16 hours, such as for a timeranging from 1 to 16 hours.

“Initial Surface Area” means the surface area of the freshly madecrystalline material before exposing it to any aging conditions.

“Initial Micropore Volume” means the micropore volume of the freshlymade crystalline material before exposing it to any aging conditions.

“Direct synthesis” (or any version thereof) refers to a method that doesnot require a metal-doping process after the zeolite has been formed,such as a subsequent ion-exchange or impregnation method.

“Defined by the Structure Commission of the International ZeoliteAssociation,” is intended to mean those structures included but notlimited to, the structures described in “Atlas of Zeolite FrameworkTypes,” ed. Baerlocher et al., Sixth Revised Edition (Elsevier 2007),which is herein incorporated by reference in its entirety.

“Selective Catalytic Reduction” or “SCR” refers to the reduction ofNO_(x) (typically with ammonia) in the presence of oxygen to formnitrogen and H₂O.

“Exhaust gas” refers to any waste gas formed in an industrial process oroperation and by internal combustion engines, such as from any form ofmotor vehicle.

DETAILED DESCRIPTION OF THE INVENTION

The microporous crystalline materials comprising a molecular sieve orzeolite having an 8-ring pore opening structure of the present inventionexhibit good hydrothermal properties, as evidenced by the stability ofthe surface area and micropore volume after exposure to hightemperatures and humidity. For example, after being treated at up to900° C. in the presence of up to 10 vol % water vapor for a time rangingfrom 1 to 16 hours, the microporous crystalline materials of the presentinvention maintain at least 80% of their initial surface area. Likewise,after the treatment, the microporous crystalline materials of thepresent invention maintain at least 80% of their initial microporevolume.

Microporous crystalline materials of the present invention may have aninitial surface area of at least 650 m²/g, such as at least 700 m²/g, oreven up to 800 m²/g.

Microporous crystalline materials of the present invention may have aninitial micropore volume of at least 0.25 cc/g, such as 0.30 cc/g.

The microporous crystalline materials of the present invention comprisemolecular sieves or zeolites, including SAPO-34, high-silica chabazite,or those having a structure defined by the Structure Commission of theInternational Zeolite Association as CHA. The SAPO-34 structure of thepresent invention may contain SiO₂ in an amount ranging from 1-20% andmay have a crystal size greater than 0.3 microns. In another embodiment,the high-silica chabazite of the present invention may have asilica-to-alumina ratio (“SAR”) greater than 15, such as ranging from15-60.

The microporous crystalline materials of the present invention alsocomprise SAPO molecular sieves and aluminosilicate zeolites having an8-ring pore opening structure defined by the Structure Commission of theInternational Zeolite Association chosen from: AEI, AFT, AFX, CHA, DDR,ERI, ITE, ITW, KFI, LEV, LTA, PAU, RHO, and UFI. These materials alsoexhibit the hydrothermal stability properties described herein, such asretaining at least 80% of their initial surface area and initialmicropore volume after being treated at temperatures of up to 900° C. inthe presence of up to 10 vol % water vapor for a time ranging from 1 to16 hours. These materials may be an aluminosilicate having a SAR greaterthan 15, such as ranging from 20-60. Alternatively, these materials mayalso be SAPO molecular sieve structures containing SiO₂ in an amountranging from 1-20%.

SAPO-34 compositions of the present invention exhibit good hydrothermaland thermal properties as identified herein. For example, after beingtreated at temperatures up to 900° C. in the presence of up to 10 vol %water vapor for 16 hours, the SAPO-34 compositions of the presentinvention maintain at least 80% of their initial surface area, such asat least 85%, at least 90%, or even at least 95%. Likewise, after thetreatment, the SAPO-34 compositions of the present invention maintain atleast 80% of their initial micropore volume, such as 85%, and even 90%of their initial micropore volume.

The microporous crystalline materials of the present invention maycomprise iron and/or copper. In one embodiment, the iron and/or copperare introduced into the microporous crystalline material by liquid-phaseor solid ion-exchange or incorporated by direct-synthesis.

The present invention also is directed to hydrothermally stablemicroporous materials comprising a molecular sieve or zeolite having an8-ring pore opening structure for SCR of NO_(x) with urea or ammonia,wherein the microporous material comprises iron and/or copper andretains at least 80% of its surface area and micropore volume afterexposure to temperatures of up to 900° C. and up to 10% water for up to1 hour. The iron oxide may comprise at least 0.20 weight percent of thetotal weight of the material, and the copper oxide may comprise at least1.0 weight percent of the total weight of the material.

In SAPO-34 compositions resulting from iron cation exchange, iron oxidecomprises at least 0.20 weight percent of the total weight of thecomposition, such as 0.25 weight percent, or even 0.30 weight percent.The resulting iron cation-exchanged SAPO-34 compositions have a surfacearea of at least 250 m²/g, such as at least 400 m²/g, and even at least600 m²/g.

In SAPO-34 compositions resulting from copper cation-exchange, copperoxide comprises at least 1.90 weight percent of the total weight of thecomposition, such as 1.95 weight percent, and even 2.00 weight percent.The resulting copper cation-exchanged SAPO-34 compositions have asurface area of at least 550 m²/g, such as at least 600 m²/g, and evenat least 650 m²/g.

The resulting cation-exchanged SAPO-34 compositions also exhibit goodhydrothermal and thermal properties, as evidenced by the stability ofthe surface area after exposure to high temperatures and humidity. Forexample, after being treated at temperatures up to 900° C. in thepresence of up to 10 vol % water vapor for up to 1 hour, the ironcation-exchanged SAPO-34 compositions of the present invention maintainat least 20% of their initial surface area, such as at least 40%, andeven at least 60%.

The microporous crystalline materials of the present invention areuseful as exhaust catalysts, such as for reduction of NO_(x) inautomotive exhaust, in part because of their good thermal andhydrothermal stability. Under extreme conditions, automotive exhaustcatalysts are exposed to heat up to and in excess of 900° C. Therefore,some automotive exhaust catalysts are required to be stable attemperatures up to and in excess of 900° C.

The present invention is also directed to a method for reduction,typically prior to discharge, of exhaust gas. As mentioned, reference to“exhaust gas” refers to any waste gas formed in an industrial process oroperation and by internal combustion engines, the composition of whichvaries. Non-limiting examples of the types of exhaust gases that may betreated with the disclosed materials include both automotive exhaust, aswell as exhaust from stationary sources, such as power plants,stationary diesel engines, and coal-fired plants.

For example, the present invention is directed to a method for SCR ofexhaust gases contaminated with NO_(x). The nitrogen oxides of exhaustgases are commonly NO and NO₂; however, the present invention isdirected to reduction of the class of nitrogen oxides identified asNO_(x). Nitrogen oxides in exhaust are reduced with ammonia to formnitrogen and water. As previously mentioned, the reduction can becatalyzed to preferentially promote the reduction of the NO_(x) over theoxidation of ammonia by the oxygen, hence “selective catalyticreduction.”

The inventive method for SCR of NO_(x) in exhaust gases comprisescontacting, in the presence of ammonia or urea, exhaust gas with ahydrothermally stable microporous crystalline material comprising amolecular sieve or zeolite having an 8-ring pore opening structure,wherein the crystalline material retains at least 80% of its surfacearea and micropore volume after exposure to temperatures of up to 900°C. in the presence of up to 10 vol % water vapor for a time ranging from1 to 16 hours. In one embodiment, the molecular sieves and zeoliteshaving an 8-ring pore opening structure comprising the microporouscrystalline material may be chosen from those structures defined by theStructure Commission of the International Zeolite Association as AEI,AFT, AFX, CHA, DDR, ERI, ITE, ITW, KFI, LEV, LTA, PAU, RHO, and UFI.

The inventive method of SCR of NO_(x) in exhaust gas also comprisescontacting, in the presence of ammonia or urea, exhaust gas with ahydrothermally stable microporous material comprising a molecular sieveor zeolite having an 8-ring pore opening structure, wherein themicroporous material comprises iron and/or copper and retains at least80% of its surface area and micropore volume after exposure totemperatures of up to 900° C. in the presence of up to 10 vol % watervapor for up to 1 hour.

In one embodiment, the inventive method for SCR of exhaust gases maycomprise (1) adding ammonia or urea to the exhaust gas to form a gasmixture; and (2) contacting the gas mixture with a microporouscrystalline composition comprising SAPO-34, having an initial surfacearea of at least 650 m²/g, wherein the surface area, after being treatedat 700-900° C. in the presence of up to 10 vol % water vapor for a timeranging from 1 to 16 hours, is at least 80% of the initial surface area;such that the NO_(x) and ammonia of the gas mixture is converted tonitrogen and water. In one embodiment, the NO_(x) of the exhaust gas aresubstantially converted.

The inventive method may be performed using a microporous crystallinecomposition comprising SAPO-34 that has been cation exchanged with iron,wherein iron oxide is at least 0.20 weight percent of the total weightof the microporous crystalline composition, and wherein the SAPO-34 hasan initial surface area of at least 250 m²/g, and wherein the surfacearea, after being treated at temperatures up to 900° C. in the presenceof up to 10 vol % water vapor for up to 1 hour, is at least 10% of theinitial surface area. Likewise, the inventive method may also beperformed using a microporous crystalline composition comprising SAPO-34cation exchanged with copper, wherein copper oxide is at least 1.0weight percent of the total weight of the microporous crystallinecomposition, and wherein the SAPO-34 has an initial surface area of atleast 500 m²/g, and wherein the surface area, after being treated attemperatures of up to 900° C. in the presence of up to 10 vol % watervapor for up to 1 hour, is at least 80% of the initial surface area.

It has been found that such methods result in the substantial conversionof NO_(x) and ammonia of the gas mixture to nitrogen and water. Themicroporous crystalline materials of the present invention showsurprisingly high stability and high reduction of NO_(x) activity overlarge pore zeolites.

The microporous crystalline materials of the present invention,including SAPO-34, may also be useful in the conversion ofoxygenate-containing feedstock into one or more olefins in a reactorsystem. In particular, the compositions may be used to convert methanolto olefins.

There is also disclosed a method of making the crystalline materialaccording to the present invention. In one embodiment, this includesmixing together an organic structural directing agent, such as atetraethylammonium hydroxide solution (e.g., 35% TEAOH), a precursor ofaluminum (e.g., pseudoboehmite alumina), and de-ionized water. To such amixture, other known ingredients, including a source of iron or copper,if desired, and silica sol can be added while stirring, to form a gel.Crystallization seeds, such as a particular zeolite, may be added to thegel to form a desired molar composition.

The gel can then be heated in an autoclave for a time and temperature toprovide a substantially pure phase composition after cooling, washing,and filtering the product. As one skilled in the art would appreciate,the product can achieve a desired SAR and/or remove organic residue uponcalcination.

The present invention is also directed to a catalyst compositioncomprising the microporous crystalline material described herein. Thecatalyst composition may also be cation-exchanged, particularly withiron or copper.

In one embodiment, the present invention is directed to a catalystcomposition comprising a microporous crystalline composition comprisingSAPO-34 having an initial surface area of at least 650 m²/g, wherein thesurface area, after being treated at temperatures of up to 900° C. inthe presence of up to 10 vol % water vapor for up to 16 hours, is atleast 80% of the initial surface area and a matrix material. In anotheraspect of the invention, the catalyst composition may comprise acation-exchanged SAPO-34 composition, particularly with iron or copper.

Any suitable physical form of the catalyst may be utilized, including,but not limited to: a channeled or honeycombed-type body; a packed bedof balls, pebbles, pellets, tablets, extrudates or other particles;microspheres; and structural pieces, such as plates or tubes.

The invention will be further clarified by the following non-limitingexamples, which are intended to be purely exemplary of the invention.

EXAMPLES Example 1 SAPO 34—Medium, Non-Uniform Crystals

Pseudoboehmite alumina, phosphoric acid, silica sol (Ludox LS30), TEAOHsolution, and deionized water were mixed together to form a gel. The gelwas stirred at room temperature for about 30 min before charged to anautoclave. The autoclave was heated to 150° C. and maintained at thetemperature for 60 hours. After cooling, the product was recovered byfiltration and washed with deionized water. The product was then driedand calcined to remove any organic residue. The resulting product wasmedium, non-uniform crystals. The resulting properties are listed belowin Table 1.

Example 2 SAPO-34—Large, Uniform Crystals

Pseudoboehmite alumina, phosphoric acid, silica sol (Nyacol 20₄0NH₄),TEAOH solution, and deionized water were mixed together to form a gel.The gel was stirred at room temperature for about 30 min before chargedto an autoclave. The autoclave was heated to 180° C. and maintained atthe temperature for 12 hours. After cooling, the product was recoveredby filtration and washed with deionized water. The product was thendried and calcined to remove organic. The resulting product was large,uniform crystals. The resulting properties are listed below in Table 1.

Example 3 High-Silica Chabazite

High-silica chabazite (structure code CHA) was synthesized according toexamples in U.S. Pat. No. 4,544,538, which is herein incorporated byreference. Pure CHA materials, with SAR of 30-40 were obtained. Afterfiltering, washing, and drying, the product was calcined at 550° C. for10 hours. To remove residual sodium, the product was slurried in 2liters of 2 M NH₄NO₃ solution and stirred at 80° C. for 2 hours. Theresulting properties are listed below in Table 1.

Example 4 SAPO-18

SAPO-18 (structure code AEI) was synthesized according to the procedureoutlined in J. Chen et al., Catal. Lett. 28 (1994) 241, which is hereinincorporated by reference. Pseudoboehmite alumina, phosphoric acid,silica sol, N,N-diisopropylethylamine (DIPEA), and deionized water weremixed to form a gel. The gel was stirred at room temperature for 120 minbefore being charged to an autoclave. The autoclave was heated to 190°C. and maintained at this temperature for 48 hours. After cooling, theproduct was recovered by filtration and washed with deionized water. Theproduct was then dried and calcined at 550° C. to remove organic. Theresulting properties are listed below in Table 1.

Comparative Example 1 Low-Silica Chabazite

Low-silica chabazite (structure code CHA) was synthesized according toexamples of U.S. Pat. No. 5,026,532, which is herein incorporated byreference. After filtering, washing, and drying, the product wascalcined at 550° C. To remove residual sodium and potassium, the productwas then washed in a solution containing 0.25 M HNO₃ and 4 M NH₄NO₃ at80° C. for 2 hours. The resulting properties are listed below in Table1.

Comparative Example 2 SAPO 34—Small, Non-Uniform Crystals

Al isopropoxide, phosphoric acid, tetraethyl orthosilicate, TEAOHsolution, and deionized water were mixed together to form a gel with thefollowing composition:0.33 SiO₂: 1.0 Al₂O₃: 1.0 P₂O₅: 1.0 TEAOH:51 H₂O

The gel was stirred at room temperature for about 30 min before chargedto an autoclave. The autoclave was heated to 180° C. and maintained atthe temperature for 12 hours. After cooling, the product was recoveredby filtration and washed with deionized water. The product was thendried and calcined to remove any organic. The resulting product wassmall crystals (less than 0.2 micron in size). The resulting propertiesare listed below in Table 1.

TABLE 1 Comparative Comparative Example 1 Example 2 Example 3 Example 4Example 1 Example 2 Gel 0.4 SiO₂: 0.6 SiO₂: 0.6 SiO₂: 0.33 SiO₂:Composition 1.0 Al₂O₃: 1.0 Al₂O₃: 1.0 Al₂O₃: 1.0 Al₂O₃: 1.0 P₂O₅: 1.0P₂O₅: 0.9 P₂O₅: 1.0 P₂O₅: 1.0 TEA 0.7 TEA 1.6 DIPEA 1.0 TEA FreshCrystals SiO₂/Al₂O₃ 28 6.3 molar ratio (SAR) Surface area 677 745 798696 577 566 (m2/g) Micropore 0.27 0.29 0.30 0.25 0.21 0.18 volume (cc/g)Acidity (mmol/g) 1.00 1.00 0.75 1.54 0.72 After 900° C. 10 vol % water16 hr aging Surface area 607 698 663 409 (m²/g) Micropore 0.22 0.27 0.240.13 volume (cc/g) Acidity (mmol/g) 0.40 0.57 0.05 0.01 Fe Ion- exchangeFe₂O₃ wt % 0.32 0.27 1.4 Surface area 306 686 793 (m²/g) After 900° C.10 vol % water 16 hr aging: Surface area 39 444 780 (m²/g) NO_(x)Conversion 10.7 10.2 88.7 (%) at 300° C. NO_(x) Conversion 25.8 35.390.4 (%) at 400° C. Cu Ion- exchange CuO wt % 2.08 1.97 2.2 1.8 2.0Surface area 558 681 747 669 557 (m²/g) After 900° C. 10 vol % water 16hr aging Surface area 13 4 669 (m²/g) After 700° C. 10 vol % water 16 hraging Surface area 544 683 762 639 10 (m²/g)Hydrothermal Aging Tests

The foregoing samples were hydrothermally aged at temperatures rangingfrom 700-900° C. in the presence of 10 vol % water vapor for between 1and 16 hours to simulate automotive exhaust aging conditions. Theactivities of the hydrothermally aged materials for NO_(x) conversion,using NH₃ as reductant, were tested with a flow-through type reactor.Powder zeolite samples were pressed and sieved to 35/70 mesh and loadedinto a quartz tube reactor. The gas stream conditions are set forth inTable 2. Reactor temperature was ramped and NO_(x) conversion wasdetermined with an infrared analyzer at each temperature interval. Theresults are set forth in Table 2 below.

TABLE 2 Ion-exchange with Cu and NO_(x) reduction with NH₃ Exam- Exam-Exam- ple 1 Example 2 ple 3 ple 4 After 700° C., 10 vol % water vapor,16 hr aging Surface area (m²/g) 544 683 762 639 NO_(x) Conversion at200° C.* 97.6 92.0 NO_(x) Conversion at 250° C.* 91.2 92.2 NO_(x)Conversion at 300° C.* 91.3 91.8 97.9 94.2 NO_(x) Conversion at 400° C.*90.5 92.8 93.7 90.6 * NH₃-SCR of NO_(x) reaction 500 ppm NO_(x); NH₃/NO= 1.0; 5 vol % conditions: O₂; balance N₂; SV = 50,000 h⁻¹. After 800°C., 10 vol % water vapor, 16 hr aging Surface area (m²/g) 517 657 NO_(x)Conversion at 250° C.** 84.7 89.8 NO_(x) Conversion at 300° C.** 88.991.3 NO_(x) Conversion at 400° C.** 88.0 86.3 ** NH₃-SCR of NO_(x)reaction 500 ppm NO_(x); NH₃/NO = 1.0; 5 vol % conditions: O₂; balanceN₂; SV = 100,000 h⁻¹. After 900° C., 10 vol % water vapor, 1 hr agingSurface area (m²/g) 632 669 NO_(x) Conversion at 200° C.*** 83.1 90.7NO_(x) Conversion at 300° C.*** 90.6 86.9 NO_(x) Conversion at 400°C.*** 83.1 79.9 *** NH₃-SCR of NO_(x) reaction 500 ppm NO; NH₃/NO = 1.0;5 vol % conditions: O₂; balance N₂; SV = 50,000 h⁻¹.

Unless otherwise indicated, all numbers expressing quantities ofingredients, reaction conditions, and so forth used in the specificationand claims are to be understood as being modified in all instances bythe term “about.” Accordingly, unless indicated to the contrary, thenumerical parameters set forth in the following specification andattached claims are approximations that may vary depending upon thedesired properties sought to be obtained by the present invention.

Other embodiments of the invention will be apparent to those skilled inthe art from consideration of the specification and practice of theinvention disclosed herein. It is intended that the specification andexamples be considered as exemplary only, with the true scope of theinvention being indicated by the following claims.

1. A hydrothermally stable microporous crystalline material comprisingSAPO-34 having a crystal size greater than 0.3 microns, which afterexposure to temperatures ranging from 700 to 900° C. in the presence ofup to 10 volume percent water vapor for a time of 16 hours, retains atleast 80% of its surface area and micropore volume and an acidity of atleast 0.35 mmol/g.
 2. A microporous crystalline material of claim 1,wherein said crystalline material comprises iron and/or copper.
 3. Amicroporous crystalline material of claim 2, wherein said iron and/orcopper are introduced into said solid by liquid-phase or solidion-exchange or incorporated by direct-synthesis.
 4. A microporouscrystalline material of claim 1, wherein said SAPO-34 contains SiO₂ inan amount ranging from 1-20%.
 5. A microporous crystalline material ofclaim 1, wherein said SAPO-34 has a crystal size ranging from 0.3 to 5.0microns.
 6. A microporous crystalline material of claim 1, having aninitial surface area of at least 650 m²/g.
 7. A microporous crystallinematerial of claim 1, having an initial micropore volume of at least 0.25cc/g.
 8. A hydrothermally stable microporous crystalline material forSCR of NO_(x)with urea or ammonia, wherein said crystalline materialcomprises iron and/or copper containing SAPO-34 having a crystal sizegreater than 0.3 microns which retains at least 80% of its surface areaand micropore volume after exposure to temperatures of up to 900 ° C. inthe presence of up to 10 volume percent water vapor for up to 1 hour. 9.A microporous crystalline material of claim 8, wherein the iron and/orcopper are introduced into said material by liquid-phase or solidion-exchange or incorporated by direct-synthesis.
 10. A microporouscrystalline material of claim 8, wherein said iron comprises at least0.20 weight percent of the total weight of said material.
 11. Amicroporous crystalline material of claim 8, wherein said coppercomprises at least 1.0 weight percent of the total weight of saidmaterial.
 12. A microporous crystalline material of claim 8, whereinsaid SAPO-34 contains 1-20% of SiO₂.
 13. A method for makingsilicoaluminophosphate molecular sieve comprising SAPO-34, said methodcomprising: mixing sources of alumina, silica, and phosphate with aTEAOH solution and water to form a gel; heating said gel in an autoclaveat a temperature ranging from 150 to 180° C. to form a product; coolingand optionally washing said product in water; calcining said product toform a molecular sieve comprising SAPO-34 having a crystal size greaterthan 0.3 microns and containing from 1-20% SiO₂, wherein said molecularsieve after exposure to temperatures ranging from 700 to 900° C. in thepresence of up to 10 volume percent water vapor for 16 hours, retains atleast 80% of its surface area and micropore volume and has an acidity ofat least 0.35 mmol/g.
 14. The method of claim 13, wherein said source ofalumina is pseudoboehmite alumina.
 15. The method of claim 13, whereinsaid source of silica is a silica sol.
 16. The method of claim 13,wherein said source of phosphate is phosphoric acid.
 17. The method ofclaim 13, further comprising a cation exchange step.
 18. The method ofclaim 17, wherein said cation is chosen from iron and copper.
 19. Themethod of claim 13, wherein said gel is heated in an autoclave at atemperature of 180° C.
 20. A microporous crystalline material of claim1, wherein said exposure comprises a temperature of 900° C.
 21. Amicroporous crystalline material of claim 1, wherein said crystallinematerial has an acidity value of at least 0.4 mmol/g after exposure. 22.A microporous crystalline material of claim 21, wherein said crystallinematerial has an acidity value ranging from 0.4 to 1.00 mmol/g afterexposure.
 23. A microporous crystalline material of claim 1, whereinsaid SAPO-34 has a crystal size ranging from 0.3 to 5.0 microns.
 24. Ahydrothermally stable microporous crystalline material comprisingSAPO-34, having a crystal size greater than 0.3 microns and an acidityof at least 0.35 mmol/g and retains at least 80% of its surface area andmicropore volume after hydrothermal aging comprising exposure totemperatures ranging from 700 to 900° C. in the presence of up to 10volume percent water vapor for a time of 1 to 16 hours.
 25. Amicroporous crystalline material of claim 24, wherein said SAPO-34contains SiO₂ in an amount ranging from 1-20%.
 26. A microporouscrystalline material of claim 24, having an initial surface area of atleast 650 m²/g.
 27. A microporous crystalline material of claim 24,having an initial micropore volume of at least 0.25 cc/g.
 28. Ahydrothermally stable microporous crystalline material of claim 8,wherein said SAPO-34 has a crystal size ranging from 0.3 to 5.0 microns.29. A microporous crystalline material of claim 2, wherein said coppercomprises about 2.0 weight percent of the total weight of said material.30. A microporous crystalline material of claim 8, wherein said coppercomprises about 2.0 weight percent of the total weight of said material.